Aluminum-zinc-alloy

ABSTRACT

The invention relates to an aluminum-zinc-alloy consisting of 50 to 75 % aluminum, 0.3 to 1.5 % manganese and, if desired, copper, nickel, silicium, lithium and chromium, remainder zinc. As compared to known alloys used for the production of bearings these new alloys are provided with an increased red hardness, high load sustaining capacity at sliding movement, lasting accuracy to gauge, high mechanical strength, adequate resistance to corrosion, essentially increased resistance to creeping, increased applicability as casting and kneading material, and may be hot shaped at high working speeds with temperatures of the range 275* to 450* C.

United States Patent Horvath et al.

ALUMINUM-ZINC-ALLOY Inventors: Gilbert l-lorvath, Linz, Austria;

Hans-Peter Mayer, Altena/Westfalen, Germany Assignee: VereinigteOsterrichische Eisen-und Stahlwerke Aktiengesellschait, Linz, AustriaFiled: Dec. 1, 1970 Appl. No.: 94,175

Foreign Application Priority Data Dec. 3, 1969 Austria 11272 ReferencesCited UNITED STATES PATENTS 7/1939 Igarashi et a1. 75/141 Nov. 20, 1973Primary Examiner-Richard 0. Dean Att0meyBrumbaugh, Graves, Donohue &Raymond [5 7 ABSTRACT The invention relates to an aluminum-zinc-alloyconsisting of 50 to 75 aluminum, 0.3 to 1.5 manganese and, if desired,copper, nickel, silicium, lithium and chromium, remainder zinc. Ascompared to known alloys used for the production of bearings these newalloys are provided with an increased red hardness, high load sustainingcapacity at sliding movement, lasting accuracy to gauge, high mechanicalstrength, adequate resistance to corrosion, essentially increasedresistance to creeping, increased applicability as casting and kneadingmaterial, and may be hot shaped at high working speeds with temperaturesof the range 275 to 450 C.

4 Claims, No Drawings ALUMlNUM-ZINC-ALLOY The invention relates to analuminum-zinc-alloy containing manganese and, if desired, further alloyelements such as copper, nickel, silicium, lithium and chromium.

Aluminum-zinc-alloys, consisting of aluminum and zinc in variouscontents, manganese and, if desired, further alloy elements, which areused as materials for slide bearings are already known.

The use of an alloy containing 38 to 75 aluminum, 0.1 to 5 copper, and,if desired, manganese, titanium, chromium and vanadium, which elementsmay entirely or partly replace the copper, remainder zinc, as bearingmaterial has been described. In the British Pat. specification No.769,484 an alloy with 43 aluminum, 57 zinc, 4 copper, 0.3 manganese and0.3 to 3 silicium is described. Further, bearing alloys onaluminum-zinc-basis with a copper addition are known, as e.g. the alloydescribed in the U.S. Pat. Nos. 2,900,288 and 2,982,677, British Pat.specification No. 725,818 and Canadian Pat. specifications Nos. 550.461and 601.992 containing 30 to 66 aluminum, and copper, the copper contentamounting to from one sixth to one quarter of the aluminum content,remainder zinc.

Further it is known to subject aluminum-zincalloys containing 35 to 55aluminum and 0 to copper, remainder zinc to a heat treatment at atemperature of from 80 to 280 C over a period of 3 to 48 hours in orderto obtain adequate sliding properties and lasting accuracy to gauge.Until now a heat treatment at higher temperatures had been considereddisadvantageous because upon cooling, after heating to 275 C, aneutectoid structure is formed, i.e. the aluminum-containing mixedcrystals segregate as two kinds of mixed crystals, one of which is richin aluminum and poor in zinc while the other is rich in zinc and poor inaluminum. This eutectoid separation goes hand in hand with a change involume which, in turn, causes an embrittlement of the material. For thesame reason these alloys cannot be hot shaped at a temperature above 275or 280 C, respectively. As a rule, these known alloys only served forthe production of castings.

Furthermore, the use of known alloys on aluminumzinc-basis is greatlyrestricted by the fact that already at relatively low workingtemperatures of e.g. 80 to 90 C they show a great decrease in hardnessand thus become useless. Some of these alloys also have thedisadvantageous property of creeping, i.e. they undergo lasting changesin shape already under a slight longterm stress.

The invention is aimed at avoiding the described disadvantages anddifficulties by creating an alloy which unites the following properties:increased red hardness (that is, hardness at elevated temperatures) ascompared to known bearing alloys on aluminum-zinc-basis, high loadsustaining capacity at sliding movement, lasting accuracy to gauge, highmechanical strength, adequate resistance to corrosion, essentiallyincreased resistance to creeping as compared to known aluminumzincbearing alloys, increased applicability both as material for casting andkneading (re-shaping operations). Further, the alloy should be hotshapeable at high working speeds, similar as this is the case withbronzes.

The alloy according to the invention with which these aims are reachedis an aluminum-zinc-alloy containing 50 to 75 preferably 55 to 65aluminum, 0.3 to l .5 preferably 0.5 to 0.8 manganese, and, if desired,

2 copper, nickel, silicium, lithium and chromium, remainder zinc. Thisalloy differs from other known alloys having a comparably high aluminumcontent in that its manganese content is limited at a maximum of Theeffect of the manganese content in the aluminum-zinc-alloy is based onthe high inclination of the aluminum-zinc solid solution to beoversaturated with manganese during the rapid solidification undernormal production conditions (particularly chill casting). Owing to thiscapacity (of the aluminum-zinc solid solution) to be oversaturated, itis e.g. effected that the manganese remains in solution but only to aparticular, low percentage which again depends on the content of otheralloy elements and does not form hard aluminides.

An examination with a micro-probe proved the uniform distribution ofmanganese in the microstructure when it is present in amounts of up to0.4 With higher contents the mentioned aluminides will separate at firstin fine (not yet harmful) and with a manganese content of more thanabout 1.5 in a coarser form.

Specific effects of manganese are: increase of tensile strength, yieldpoint, elongation, resistance to wear, red hardness and resistance tocorrosion. The manganese addition within the limits according to theinvention furnishes an alloy on aluminum-zinc-basis with propertieswhich are otherwise not obtainable or only with essentially moreexpensive alloys. Owing to the high content of aluminum of the alloyaccording to the invention and the therefore only very small change involume during the eutectic transformation of the aluminumzinc mixedcrystal it is possible and advantageous to carry out heat treatmentsalso above a temperature of 275 C without the occurrence of anembrittlement in the material.

The copper content of the alloy according to the invention may amount toup to 3 The nickel content of the alloy according to the invention mayamount to up to 1 The silicium content of the alloy according to theinvention may amount to up to 0.6

The lithium content of the alloy according to the invention may amountto up to 0.1

The chromium content of the alloy according to the invention may amountto up to 0.5

Thus, a preferred embodiment for producing shaped bodies from alloys ofthe described kind by hot shaping resides in that a shaping temperatureof 275 to 450 C, preferably of 330 to 350 C, is applied. Owing to thehigher temperature for hot shaping it is possible to work with anessentially higher shaping speed than may be employed with known alloys.Shaping may also be effected by extrusion, traction and rolling.

The shaped bodies may also be produced from the described alloys bycasting and subsequent heat treatment, the heat treatment being carriedout at a temperature of 290 to 380 C, preferably 330 to 350 C. Theduration of the heat treatment may amount to several hours up to 48hours.

The invention is illustrated by the following Examples.

EXAMPLE 1;

By melting aluminum, manganese and zinc, an alloy of the followingcomposition is produced which is used for manufacturing a bearingbushing with an inner diameter of 30 mm and an outer diameter of 40 mm.

The alloy is composed of:

remainder Zn.

After annealing for 40 hours at 330 C and cooling at the air themechanical data of the alloy are the follow- The bearing bushings ranfor 2 hours under constant drop oil lubrication and then for 20 hourswithout lubrication against a shaft of natural hardness made ofstructural steel having a tensile strength of 60 kp/mm (DIN St 60); intwo test series the peripheral velocity once amounted to 1.5 m/sec. andthen 0.3 m/sec. at a specific load per surface unit of 22 kp/cm Noimpairment of the shaft was discernable.

EXAMPLE 2:

The composition of an alloy is the following:

remainder Zn.

After annealing for 40 hours at 330 C and air cooling the mechanicaldata of the alloy are the following:

tensile strength o-B 29.2 kp/mm yield point S 23.7 kp/mm elongation 05 8hardness, Brinell number HB 109 kp/mm at 25 C hardness, hot Brinellnumber:

50 C 75 100 C 125 C 150 C (HB, kplmm 98 91 82 73 65 The followingExamples show the influence of slight contents of Cu, Ni and Si on themechanical properties of the alloys according to the invention.

EXAMPLE 3:

The composition of an alloy is the following:

remainder Zn.

After annealing for 40 hours at 330 C and air cooling the mechanicaldata of the alloy are the following:

tensile strength oB 30.6 kplmm yield point GS 24.3 kp/mm elongation 0'57 hardness, Brinell number [-18 1 12 kp/mm Example 4:

The composition of an alloy is the following:

remainder Zn.

After annealing for 10 hours at 330 C and air cooling the mechanicaldata of the alloy are the following:

tensile strength 08 40.2 kp/mm yield point as 33.4 kp/mm elongation 0'55 hardness, Brinell number HB 115 kp/mm EXAMPLE 5:

The composition of an alloy is the following:

remainder Zn. The mechanical data of the alloy in the as-cast conditionare the following:

tensile strength 08 33.7 kp/mm yield point as 26.5 kplmm elongation 05 4bending fatigue strength: BW 9.5 kp/mm hardness, hot Brinell number:

25 C 50 C C C 125 C 150 C (HB, kp/mm):

107 98 85 79.5 65 When this alloy is subjected to a heat treatment at300 C for 8 hours the mechanical data change as follows:

tensile strength 013 38.0 kp/mmE yield point 0'S 32.0 kp/mm elongation(r5 8 When the alloy is shaped as kneading material at 340 C themechanical data are as follows:

tensile strength o-B 46.0 kp/mm yield point o-S 39.2 kp/mm,

elongation 05 14 bending fatigue strength: BW 11.5 kp/mm hardness, hotBrinell number: 7

25 C 50 C 75 C 100 C C C (HB, kp/mm EXAMPLE 6:

The composition of an alloy is the following:

55 A1, 0.3 Cu,

remainder Zn.

The mechanical data of the alloy in the as-cast condition are thefollowing:

tensile strength 08 37.1 kp/mm",

yield point 08 33.1 kp/mm,

I elongation 05 4 hardness, Brinell number HB ll 1 kp/mm EXAMPLE 7:

The composition of an alloy is the following:

remainder Zn. After annealing for 8 hours at 330 C and air cooling themechanical data of the alloy are the following:

tensile strength a8 37.3 kp/mm,

yield point GS 30.5 kp/mm,

elongation 05 2.7

hardness, Brinell number HB 115 kp/mm As is readily apparent from theabove data, also the wherein the aluminum content amounts to from 55 to3. The aluminum-zinc-alloy set forth in claim 1,

wherein the manganese content amounts to from 0.5 to

4. An aluminum-zinc-alloy consisting essentially of 50 to aluminum,

0.3 to 1.5 manganese,

0 to 3 copper,

0 to l nickel,

0 to 0.6 silicon,

0 to 0.1 lithium,

0 to 0.5 chromium,

balance zinc.

I v UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,775,502 Dated November 20, 1975 Inven fl Horvath, et al.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

First page, Item ['75:], "Osterrichisohe Eisen-und" should be--Osterreichische Eisenund-. Col. 1, line 19, "Pat." should read--Pats.-. Col. 5, lines 2A and 25, the hardness indications shouldappear beneath the temperatures to which they correspond, as follows:

I v 50C 75C 100 c lC 150C C01. 5, lines 51 and 52, the hardnessindications should appear beneath the temperatures to which theycorrespond, as. follows:

(HE, kp/mm C 75 100 c 125C 150 c p/ 98 91 82 75- 5 Col. b, I line 52."remainder Zn." should be indented on the line below "0 .3 N11,"; lineshould not be indented. Col. LI, lines #2, +5 and A, the hardnessindications should appear beneath the temperatures to which theycorrespond, as follows:

, 25 0' 50 c 0 0 c c (HlB, kp/mm a 120 107 98 85 79.5 65

Column LI, line 51,- "elongation c 5 8%" should be indented, and

"when the alloy should be brought over to the margin; line 55, "follows:should be brought over to the margin; lines 62, 65 and 6A, the hardnessindications should appear beneath the temperatures to which theycorrespond, as follows:

OHM PC4050 uscoMM-oc 60376-P69 9 U.S. GOVERNMENT fIUNTING OFFICE II!O3-33l.

U TEDsTATEs PATENTOFFICE f 1 CERTIFICATE OF CORRECTION Patent No.5,775,502 'Dated November 20, 1973 lnvent fl Horvath. et el.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

' C C C c C c (HB, kp/mm v 116 108 99 89 76 65 C01. 5, line 25,["f'emainder Zn." should be indented, and "After annealing "should bebrought over to the margin.

Signed and sealed this 16th day of July 197A.

(SEAL) V Attest: I

MCCOY M. GIBSON, JR. 0. MARSHALL DANN Attesting Officer Commissioner ofPatents USCOMM-DC 60376-P69 FORM PO-1050 (10-69) v w as, covznnusm'ram-mac orrlc: IS! o-au-au.

2. The aluminum-zinc-alloy set forth in claim 1, wherein the aluminumcontent amounts to from 55 to 65 %.
 3. The aluminum-zinc-alloy set forthin claim 1, wherein the manganese content amounts to from 0.5 to 0.8 %.4. An aluminum-zinc-alloy consisting essentially of 50 to 75 % aluminum,0.3 to 1.5 % manganese, 0 to 3 % copper, 0 to 1 % nickel, 0 to 0.6 %silicon, 0 to 0.1 % lithium, 0 to 0.5 % chromium, balance zinc.